Polyester compounds obtained from aliphatic diols and aliphatic dicarboxylic acids are useful as plasticizers for synthetic resins and have been widely applied particularly to chlorine-containing resins, such as vinyl chloride resins.
A polyester plasticizer providing improved low temperature flexibility that is prepared by using 2-methyl-1,3-propanediol as an aliphatic diol is disclosed in JP-A-61-78827. However, the proposed polyester plasticizer has low plasticization efficiency and fails to impart sufficient oil resistance to chlorine-containing resins.